This invention relates to a valve actuating mechanism for internal combustion engines and more particularly to an improved arrangement for actuating plural valves for a given combustion chamber and for lubricating the actuating mechanism.
It is well known that the specific output of an internal combustion engine may generally be improved by employing plural valves for each combustion chamber. By using two or more intake and/or exhaust valves, it is possible to obtain a greater flow area for a given surface area and higher rotating speeds due to reduced inertia. Certain practical limitations, however, have limited the use of such plural valve applications. Among the main of these limiting factors is the geometric relationship of the combustion chamber and the associated actuating mechanism. That is, if plural valves are employed, an arrangement should be provided so as to insure that the valves will not interfere with each other during their opening and closing operation and, at the same time, the ratio of the surface volume of the combustion chamber to its clearance volume should be kept relatively small. In addition, the clearance volume itself should be maintained as small as possible so as to permit the use of high compression ratios. These factors have practically limited the valving arrangements of internal combustion engines to two intake and/or exhaust valves per cylinder.
Recently, it has been proposed to provide a valve actuating mechanism and valve placement that will permit the use of three or more intake and/or exhaust valves for a single combustion chamber. One way this can be done is by employing a single camshaft that operates the three or more valves with the operation of one of the valves being done directly through a tappet follower and the operation of other of the valves being done through rocker arms. A very practical arrangement for achieving this purpose is shown in the copending application entitled "Actuating Mechanism For Multiple Valve Internal Combustion Engine, filed in my name along with Kazuo Aoi as a joint inventor, Ser. No. 717,832, Filed 3/29/85, and assigned to the assignee of this application. As described in that copending application, the desired valve placement may be achieved and a compact actuating mechanism employed by operating one valve directly through a thimble tappet and the other two valves by means of rocker arms, all from the same camshaft. Although this arrangement has many advantages, it is necessary to provide good lubrication for all of the valve actuating components.
It is, therefore, a principal object of this invention to provide an improved actuating mechanism for multiple valve internal combustion engines.
It is a yet further object of this invention to provide an improved multiple valve actuating mechanism and a lubricating system for it.
It is a yet further object of this invention to provide an improved and simplified lubricating arrangement for the actuating mechanism for a multiple valve internal combustion engine.